This invention relates to a method of making an end connection to a fluid power cylinder and the product resulting therefrom and, more particularly, to a permanent connection wherein the component parts are integrated in such a fashion as to resist substantial shock forces tending to destroy the connection.
This invention relates to that type of fluid power cylinder which has come to be designated "non-repairable". As such, the various components of the cylinder are permanently ingtegrated at the time of manufacture so that the resulting cylinders are relatively inexpensive and can be readily replaced -- as contrasted to being repaired. Although the cost of repair labor is high, it is still necessary to provide a relatively inexpensive cylinder unit which can be discarded after it has worn out, or otherwise failed. Since these cylinders often are in installations where they encounter impact loads at very high rates of cycling, it is of real importance to have the parts well integrated, particularly the end caps and the cylinder casing. Failure of this joint or connection could release the piston rod, for example, like a projectile with the capability of significant damage and possible injury to the persons in the vicinity. Thus, those in this art faced a dilemma; the parts had to be inexpensive and readily integrated on the one hand yet, on the other hand, the connection had to be rugged and strong enough to withstand the impact load.
For many years the art has employed a simple technique of deforming (as by rolling) the end portion of the casing into a sloping-sided trough provided in the end cap, and thereafter peening (again as by rolling) a portion of the end cap over the rolled portion of the casing. This has been deemed inadequate by the workers in this art to withstand the severe and repetitive shock loads. For example, the well known construction referred to above was augmented by a clamping ring in U. S. Pat. No. 3,811,367. Even this construction was deemed less than satisfactory because in a subsequent patent (U. S. Pat. No. 3,848,325) the encircling band was further rigidified through the use of annular ribs.
I have discovered that the problem of satisfactory connection between the tubing and end cap can be advantageously solved through the use of a differently contoured trough -- more particularly an annular recess provided in the shank which has a channel shape so as to develop a pronounced right angled step in the casing end portion so as to provide the desired locking securement. According to the method of the invention, the aforementioned right angled step is developed through metal deformation (again as by rolling) but with the imposition of axial force on the tubing which results in the advantageous cold working and flow of metal from the casing into the area of the desired joint.
Other advantages and objects of the invention may be seen in the details set down in the ensuing specification.